EP0540466B1 - Solvent-free curable resin compositions, especially for the production of prepregs - Google Patents

Abstract

The invention relates to an essentially solvent-free, curable resin composition, in particular for the production of prepregs, which contains more than 45% by weight of substances which are solid at least at room temperature or lower temperatures, and, in addition to conventional additives, comprises solid epoxy resins or a mixture of liquid and solid epoxy resins, at least one UV-sensitive initiator compound for polymerisation of the epoxy resins, which has the formula I: <IMAGE> in which a and b, independently of one another, are 1 or 2, R<1> is a pi -arene, R<2> is a pi -arene, an indenylanion or a cyclopentadienylanion, [X]<(-)> is an anion [LQm]<(-)> or an anion of a partly or perfluorinated aliphatic or aromatic sulphonic acid, L is B, P, As or Sb, Q is F, where some of the radicals Q may alternatively be hydroxyl groups, and m corresponds to the valency of L increased by one, and at least one further compound which contains one or more carboxyl groups, and can be converted into a flowable state by warming to a temperature in the range from 60 to 140 DEG C in the absence of UV and without a solvent being added to it, and, by cooling to at most room temperature and in the absence of UV, can be converted from this state into a solid composition which has a softening point of -3 DEG C or above, is in a chemically essentially unchanged form and is tack-free or virtually tack-free at room temperature. The compositions can be used, for example, to produce prepregs in a simple manner without using a solvent.

Description

The present invention relates to an essentially solvent-free curable Resin composition, in particular for the production of prepregs and a process for the preparation of the prepregs with this resin composition.

"Prepregs" are fiber-reinforced materials that are curable Contain resin composition and with the help of actinic radiation and / or heat, optionally in contact with suitable other materials to form a composite material can be processed.

enthält, oder mit der Lösung einer entsprechenden festen Mischung in einem inerten Lösungsmittel in innigen Kontakt bringt und das mit der härtbaren Mischung getränkte Fasermaterial gegebenenfalls trocknet. Danach können die Prepregs zu Verbundkörpern weiterverarbeitet werden, wobei die härtbare Mischung, nachdem sie bevorzugt zunächst aktinischer Strahlung ausgesetzt wurde, durch Anwendung von Wärme ausgehärtet werden muss. In Formel I sind a und b unabhängig voneinander 1 oder 2, R¹ ist ein π-Aren, R² ein π-Aren, ein Indenylanion oder ein Cyclopentadienylanion bedeutet, [X]^⊖ ist ein Anion [LQ_m]^⊖ oder ein Anion einer teil- oder perfluorierten aliphatischen oder aromatischen Sulfonsäure, L steht für B, P, As oder Sb, Q steht für F, wobei ein Teil der Reste Q auch Hydroxylgruppen sein können, und m entspricht der um Eins vergrösserten Wertigkeit von L.From EP-A-0 323 584 it is known to produce prepregs by adding a fibrous carrier material either with a liquid, solvent-free curable mixture containing an epoxy resin and a compound of formula I as a hardener

contains, or brings into intimate contact with the solution of a corresponding solid mixture in an inert solvent and the fiber material impregnated with the curable mixture optionally dries. The prepregs can then be processed further to form composite bodies, the curable mixture having to be exposed to actinic radiation first, has to be cured by application of heat. In formula I, a and b are independently 1 or 2, R ¹ is a π-arene, R ^{2 is} a π-arene, an indenyl anion or a cyclopentadienyl anion, [X] ^⊖ is an anion [LQ _m ] ^⊖ or an anion a partially or perfluorinated aliphatic or aromatic sulfonic acid, L stands for B, P, As or Sb, Q stands for F, some of the residues Q can also be hydroxyl groups, and m corresponds to the value of L. increased by one

A major disadvantage here is that solid mixtures with which dry and so that prepregs that can be stored in the long term can also be produced with the help of an inert organic solvent can be applied as a carrier, which corresponding effort for proper and, in particular, emission-free drying of the prepregs. The Disclosed liquid, solvent-free mixtures, such as. B. according to the Embodiments 6 and 8 of the considered patent application are used in contrast, only suitable for a continuous procedure in which the curable mixture impregnated fiber material almost immediately to the composite material is processed further. However, these liquid mixtures do not allow production dry prepregs, since this is the liquid curable that adheres to the fiber material Resin composition through partial pre-crosslinking only in a solid state would have to be transferred. Such a pre-crosslinking that is used in prepreg technology the name "B-level formation" is also known, but would use a second hardener with different reactivity. In addition, it is only with today great effort possible to control the B-level formation so that prepregs with real reproducible properties can be obtained.

An additional disadvantage of the compositions described above is that they are used in the Heat treatment at relatively high temperatures for adequate curing need. So these compositions require even after treatment with actinic radiation, which usually leads to a reduction in the curing temperature leads, still temperatures in the range of 170 to 180 ° C for good Hardening. The use of such high temperatures has, among other things very high energy consumption or closes z. B. the use thermally less stable materials than components of composite bodies when the body to be produced using the prepregs mentioned.

EP-A-0 321 407 describes thermally curable compositions based on Epoxy resin and a compound of formula I in the meaning given above known, which - after activation by actinic radiation - is also essential lower temperature than 170 to 180 ° C can be cured, e.g. B. at 100 ° C. These compositions contain, in addition to the components mentioned a flexible terminated with an average of two carboxyl groups per molecule Polyester and are suitable as adhesives and coating agents. Are preferred here Compositions containing liquid epoxy resins mixed with solid or semi-solid Contain epoxy resins. The publication is only the application method Use of the compositions in liquid or in the form of a solution removable, the disadvantages of which have already been mentioned above.

The object of the present invention is to overcome the disadvantages of the prior art described above to fix the technology, d. H. the production of tack-free or almost tack-free and long storable prepregs, which can also be used at temperatures below approx. 140 Allow ° C to harden in the usual time so that composite bodies with good application properties can be obtained without the use of Solvents and / or the need for partial curing up to the B level to enable.

The present invention therefore relates to a curable resin composition with less than 2% by weight of solvent for the production of prepregs, which has a proportion of more than 45% by weight (% by weight) of substances which are solid at least at room temperature and which, in addition to conventional additives, consist of solid epoxy resins or a mixture of liquid and solid epoxy resins, at least one initiator compound sensitive to UV radiation for the polymerization of the epoxy resins and at least one further compound which has one or more carboxyl groups, the initiator compound for the polymerization of the epoxy resins having the formula I: [R 1 (Fe II R 2nd ) a ] from + from [X] - where a and b are independently 1 or 2, R ^{1 is} a π-arene, R ^{2 is} a π-arene, an indenyl anion or a cyclopentadienyl anion, [X] ^- an anion [LQ _m ] ^- or an anion of a partially or perfluorinated aliphatic or aromatic sulfonic acid, L is B, P, As or Sb, Q is F, part of the radicals Q can also be hydroxyl groups, and m corresponds to the value of L increased by one, the proportion of solid epoxy compounds, based on the total weight of the epoxy resins in the composition is 50 percent by weight or greater than 50 percent by weight and the composition by heating to a temperature in the range from 60 to 140 ° C with UV exclusion and without adding a solvent, in one It can be converted into a state in which it has a viscosity of at most 3500 mPa.s, and from this state it cools down to a maximum of room temperature and with UV exclusion into a still unused state hardened, at room temperature tack-free or almost tack-free, solid mass with a softening point of minus 3 ° C and higher, can be transferred.

The compositions according to the invention contain practically no solvent, with Exception of very small amounts (less than about 2% by weight) of solvent, which often cannot be avoided, e.g. B. because they are introduced by such additives that are usually available in dissolved form, such as wetting agents.

The viscosity of the compositions is generally at most 3500 mPa · s because the composition in this state, optionally under pressure Fiber material commonly used for prepregs, e.g. B. fiberglass fabric, can easily penetrate. Compositions which are preferred Heating to a temperature in the range between 60 and 140 ° C in one state are convertible in that they have a viscosity of at most 1200 mPa · s, in particular of have a maximum of 600 mPa · s. However, the compositions should be at 60 ° C also not be too thin. A lower limit for the viscosity of is preferred 200, especially 400 mPa · s.

With "room temperature" is the place of use of the composition without the Use of a special cooling device meant temperature. It will be in generally between 10 and 25 ° C.

"Tack-free or almost tack-free mass at room temperature" means that the Masses can be and are generally sticky, but only so little that they are easily peeled off again from a substrate to which they adhere can. Slight stickiness is often even desirable, since prepregs made from such Material in an unhardened state is particularly easy in the desired shape are fixable. The mass softening point is preferably above 0 ° C.

Suitable epoxy resins for the compositions according to the invention are: Usually all epoxy resins with an average of at least two 1,2-epoxy groups in the Molecule. However, N-glycidyl compounds impair the effect of the Initiator compounds of formula I (catalyst poison) and are therefore little or no not suitable. Due to toxicological considerations, triglycidyl isocyanurate and Epoxy resins containing epoxy groups within cycloaliphatic rings, such as. B. Bis- (2,3-epoxicyclopentyl) ether, and in connection with epoxy resins based on Bisphenol A are used, less preferred.

I) Polyglycidyl- und Poly-(β-methylglycidyl)-ester erhältlich durch Umsetzung einer Verbindung mit mindestens zwei Carboxylgruppen im Molekül und Epichlorhydrin bzw. Glycerindichlorhydrin bzw. β-Methylepichlorhydrin. Die Umsetzung erfolgt zweckmässig in der Gegenwart von Basen. Als Verbindung mit mindestens zwei Carboxylgruppen im Molekül können aliphatische, cycloaliphatische oder aromatische Polycarbonsäuren verwendet werden. Beispiele für diese Polycarbonsäuren sind weiter unten als Bildungskomponenten von für die Erfindung geeigneten Polyestern aufgeführt.

II) Polyglycidyl- oder Poly-(β-methylglycidyl)-ether erhältlich durch Umsetzung einer Verbindung mit mindestens zwei freien alkoholischen Hydroxylgruppen und/oder phenolischen Hydroxygruppen und einem geeignet substituierten Epichlorhydrin unter alkalischen Bedingungen, oder in Anwesenheit eines sauren Katalysators und anschliessender Alkalibehandlung. Ether dieses Typs leiten sich beispielsweise ab von acyclischen Alkoholen mit mindestens 3, bevorzugt mindestens 6 Kohlenstoffatomen, z. B. von Poly-(oxyethylen)-glykolen, Poly-(oxypropylen)-glykolen, Butan-1,4-diol, Poly-(oxytetramethylen)-glykolen, Hexan-1,6-diol, Hexan-2,4,6-triol, Glycerin, 1,1,1-Trimethylolpropan, Pentaerythrit, Sorbit, sowie von Polyepichlorhydrinen. Sie leiten sich aber auch beispielsweise ab von cycloaliphatischen Alkoholen wie 1,3- oder 1,4-Dihydroxycyclohexan, Bis-(4-hydroxycyclohexyl)-methan, 2,2-Bis(4-hydroxycyclohexyl)-propan oder 1,1-Bis-(hydroxymethyl)-cyclohex-3-en. Die Epoxidverbindungen können sich auch von einkernigen Phenolen ableiten, wie beispielsweise von Resorcin oder Hydrochinon; oder sie basieren auf mehrkernigen Phenolen wie beispielsweise auf Bis-(4-hydroxyphenyl)-methan (Bisphenol F), 4,4'-Dihydroxydiphenyl, Bis-(4-hydroxyphenyl)-sulfon, 1,1,2,2-Tetrakis-(4-hydroxyphenyl)-ethan, 2,2-Bis-(4-hydroxyphenyl)-propan (Bisphenol A),2,2-Bis-(3,5-dibrom-4-hydroxyphenyl)-propan sowie auf Novolaken erhältlich durch Kondensation von Aldehyden, wie beispielsweise Formaldehyd, Acetaldehyd, Chloral oder Furfuraldehyd mit Phenolen, wie insbesondere Phenol oder Kresol, oder mit Phenolen, die im Kern mit Chloratomen oder C₁-C₉Alkylgruppen substituiert sind, wie beispielsweise 4-Chlorphenol, 2-Methylphenol oder 4-tert.Butylphenol oder erhältlich durch Kondensation mit Bisphenolen, so wie oben beschrieben.

III) Poly-(S-glycidyl) Verbindungen, insbesondere Di-S-glycidylderivate, die sich von Dithiolen oder Bis-(4-mercaptomethylphenyl)-ether ableiten.

Epoxy resins which are very suitable for the invention are, for example:

I) Polyglycidyl and poly (β-methylglycidyl) esters obtainable by reacting a compound with at least two carboxyl groups in the molecule and epichlorohydrin or glycerol dichlorohydrin or β-methylepichlorohydrin. The reaction is conveniently carried out in the presence of bases. Aliphatic, cycloaliphatic or aromatic polycarboxylic acids can be used as the compound having at least two carboxyl groups in the molecule. Examples of these polycarboxylic acids are listed below as forming components of polyesters suitable for the invention.

II) Polyglycidyl or poly (β-methylglycidyl) ether obtainable by reacting a compound with at least two free alcoholic hydroxyl groups and / or phenolic hydroxyl groups and a suitably substituted epichlorohydrin under alkaline conditions, or in the presence of an acidic catalyst and subsequent alkali treatment. Ethers of this type are derived, for example, from acyclic alcohols having at least 3, preferably at least 6, carbon atoms, e.g. B. of poly (oxyethylene) glycols, poly (oxypropylene) glycols, butane-1,4-diol, poly (oxytetramethylene) glycols, hexane-1,6-diol, hexane-2,4,6 -triol, glycerin, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol, and of polyepichlorohydrins. However, they are also derived, for example, from cycloaliphatic alcohols such as 1,3- or 1,4-dihydroxycyclohexane, bis (4-hydroxycyclohexyl) methane, 2,2-bis (4-hydroxycyclohexyl) propane or 1,1-bis - (hydroxymethyl) cyclohex-3-ene. The epoxy compounds can also be derived from mononuclear phenols, such as, for example, resorcinol or hydroquinone; or they are based on polynuclear phenols such as, for example, bis (4-hydroxyphenyl) methane (bisphenol F), 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) sulfone, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane and on novolaks available from Condensation of aldehydes, such as, for example, formaldehyde, acetaldehyde, chloral or furfuraldehyde, with phenols, such as, in particular, phenol or cresol, or with phenols which are essentially substituted with chlorine atoms or C ₁ -C ₉ alkyl groups, such as, for example, 4-chlorophenol, 2-methylphenol or 4-tert-butylphenol or obtainable by condensation with bisphenols as described above.

III) Poly (S-glycidyl) compounds, in particular di-S-glycidyl derivatives, which are derived from dithiols or bis (4-mercaptomethylphenyl) ether.

However, epoxy resins can also be used in which the 1,2-epoxy groups are attached different heteroatoms or functional groups are bound; to this Compounds include, for example, the glycidyl ether glycidyl ester of salicylic acid.

These epoxy resins are known per se or can be prepared by known processes getting produced.

The mixtures according to the invention generally contain 60 to 98% by weight Epoxy resins, in particular 75 to 98 wt .-%, e.g. B. 80 to 90 wt .-%. The proportion fixed Epoxy resins is 50 wt .-%, based on the total weight of the Epoxy resins, and larger, e.g. B. greater than 60 wt .-% or 70 wt .-%. One can also only use solid epoxy resins if they have a sufficiently low softening temperature (generally below 140 ° C).

A mixture of liquid and solid epoxy resins that is part of the Forms compositions according to the invention, the mixture of one or more liquid epoxy resins with one or more solid epoxy resins.

Compositions which are either liquid epoxy resins are particularly preferred Contain glycidyl esters or diglycidyl ethers, which differ from bisphenol A or bisphenol F derive. Compositions which are in the form of solid epoxy resins are also preferred Contain polyglycidyl ethers that differ from bisphenol A, bisphenol F or from Derive epoxy novolaks, in particular epoxyphenol and epoxycresol novolaks.

For the compounds of the formula I, π-arenes R ¹ and R ^{2 are} preferably carbocyclic-aromatic hydrocarbons having 6 to 24 carbon atoms, in particular having 6 to 12 carbon atoms, or heterocyclic-aromatic hydrocarbons having 4 to 11 carbon atoms and one or two S - And / or O atoms into consideration, these groups optionally being replaced by identical or different monovalent radicals, such as halogen atoms, preferably chlorine or bromine atoms, or C ₁ -C ₈ alkyl, C ₁ -C ₈ alkoxy or phenyl groups or can be substituted several times, preferably once or twice. These π-arene groups can be mononuclear, condensed multinuclear or uncondensed multinuclear systems, the nuclei in the latter systems being directly or via bridge members, such as -CH ₂ -, -C (CH ₃ ) ₂ -, -O-, -S- , -SO ₂ -, -CO- or -CH = CH-, can be linked. R ² can also be an indenyl anion and in particular a cyclopentadienyl anion, it also being possible for these anions to be mono- or polysubstituted, preferably mono- or disubstituted, by the same or different monovalent radicals, as mentioned above as substituents for π-arenes. The alkyl or alkoxy substituents can be straight-chain or branched. Typical alkyl or alkoxy substituents are methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl and n-octyl, methoxy, ethoxy, n-propoxy Called isopropoxy, n-butoxy, n-hexyloxy and n-octyloxy. Alkyl and alkoxy groups with 1 to 4 and in particular 1 or 2 carbon atoms in the alkyl parts are preferred. Preferred substituted π-arenes or substituted indenyl or cyclopentadienyl anions are those which contain one or two of the above-mentioned substituents, in particular methyl, ethyl, n-propyl, isopropyl, methoxy or ethoxy groups. The same or different π-arenes may be present as R ¹ and R ² .

Examples of suitable π-arenes are benzene, toluene, xylenes, ethylbenzene, cumene, Methoxybenzene, ethoxybenzene, dimethoxybenzene, p-chlorotoluene, m-chlorotoluene, chlorobenzene, Bromobenzene, dichlorobenzene, trimethylbenzene, trimethoxybenzene, naphthalene, 1,2-dihydronaphthalene, 1,2,3,4-tetrahydronaphthalene, methylnaphthalene, methoxynaphthalene, Ethoxynaphthalene, chloronaphthalene, bromnaphthalene, biphenyl, stilbene, indene, 4,4'-dimethylbiphenyl, fluorene, phenanthrene, anthracene, 9,10-dihydroanthracene, Triphenyl, pyrene, perylene, naphthacene, corones, thiophene, chromium, xanthene, thioxanthene, Benzofuran, benzothiophene, naphthothiophene, thianthrene, diphenylene oxide and Diphenylene sulfide.

Examples of anions of substituted cyclopentadienes are the anions of methyl, Ethyl, n-propyl and n-butylcyclopentadiene or the anions of dimethylcyclopentadiene. Preferred anions are the anion of the unsubstituted indene and in particular of unsubstituted cyclopentadiene.

The index a is preferably 1. The index b is preferably 1. When a is 2, R ^{2 is} preferably each the optionally substituted indenyl anion or in particular the cyclopentadienyl anion.

X ^⊖ is preferably the anion of a perfluoroaliphatic or perfluoroaromatic sulfonic acid and very particularly [LQ _m ] ^⊖ , as defined above.

Examples of anions of perfluoroaliphatic or perfluoroaromatic sulfonic acids are CF ₃ SO ₃ ^⊖ , C ₂ F ₅ SO ₃ ^⊖ , nC ₃ F ₇ SO ₃ ^⊖ , nC ₄ F ₉ SO ₃ ^⊖ , nC ₆ F ₁₃ SO ₃ ^⊖ , nC ₈ F ₁₇ SO ₃ ^⊖ , C ₆ F ₅ SO ₃ ^⊖ and CF ₃ C ₆ F ₄ SO ₃ ^⊖ . CF ₃ SO ₃ ^{⊖ is preferred} .

Examples of particularly preferred anions [LQ _m ] ^⊖ are PF ₆ ^⊖ , AsF ₆ ^⊖ , SbF ₆ ^⊖ and SbF ₅ (OH) ^⊖ . PF ₆ ^⊖ , SbF ₆ ^⊖ , in particular SbF ₆ ^⊖ are very particularly preferred. Compositions containing compounds of the formula I with SbF ^⊖ ₆ as ^anions can be cured by irradiation at very low temperatures after they have been ^unblocked .

The compounds of the formula I are known per se or can be prepared analogously to known compounds. The preparation of the salts with X ^⊖ = [LQ _m ] ^⊖ is described for example in EP-A-94,915. Compounds of the formula I with other anions can be prepared in deviation from the processes described therein by introducing another anion of the acid HX in a manner known per se instead of an anion of a complex acid; X has the meaning defined above.

In some cases, it may be particularly advantageous to use compositions according to the invention which contain more than one iron arene compound of the formula I, these compounds, for. B. each have different anions [X ^⊖ ]. Examples of this are mixtures of iron arene salts based on the anions SbF ₆ ^⊖ and CF ₃ SO ₃ ^⊖ and in particular based on PF ₆ ^⊖ and SbF ₆ ^⊖ . With such mixtures, for example, the curing conditions of compositions according to the invention and the properties of curing products which are produced with the aid of the compositions can be optimally controlled.

The total content of the compositions of compounds of formula I is usually between 0.5 and 10% by weight, preferably between 1 and 5% by weight.

As compounds which have one or more carboxyl groups, z. B. usual low molecular weight carboxylic acids in question. The carboxylic acids can Be solid and liquid at room temperature. They preferably have a molecular weight of 45 up to 250 g per carboxyl equivalent, in particular from 45 to 100 g. Are suitable for. B. Lactic acid (liquid at room temperature) or benzoic acid, salicylic acid, oxalic acid, Malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, malic acid, Tartaric acid, maleic acid, fumaric acid. Lactic acid, adipic acid are particularly preferred and fumaric acid.

Free carboxyl groups are also very suitable, especially with an average of at least two carboxyl-terminated polyesters, such as those e.g. B. in EP-A-0 321 407. The latter polyester namely lead under among other things to greatly improved adhesive properties. The polyester can Room temperature be liquid or semi-solid or solid. The polyesters can be amorphous or be semi-crystalline. Their softening point is preferably below 100 ° C and they usually have number average molecular weights of 250 to 15,000, preferably from 500 to 2500. Their acid number is generally 0.1 to 5 equivalents / kg, preferably 0.1 up to 2.0 equiv./kg. The viscosity (according to Epprecht) of these polyesters is generally lower than 2000 mPa · s (at 80 ° C).

The polyesters are derived from aliphatic or cycloaliphatic polyols and aliphatic, cycloaliphatic or aromatic polycarboxylic acids.

In the case of the polyols, preference is given to using low-molecular and prepolymers Assembly components.

Examples of low molecular weight aliphatic diols are α, ω-alkylene diols, such as ethylene glycol, Propane-1,2-diol, propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, neopentyl glycol, Hexane-1,6-diol, octane-1,8-diol, decane-1,10-diol or dodecane-1,12-diol. Examples of low molecular weight cycloaliphatic diols are 1,3- or 1,4-dihydroxycyclohexane, 1,4-cyclohexane dimethanol, bis (4-hydroxycyclohexyl) methane or 2,2-bis (4-hydroxycyclohexyl) propane. Examples of small molecules with higher functionality Alcohols are 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerin, pentaerythritol or 1,3,5-trihydroxybenzene.

Prepolymer components are generally hydroxyl-terminated Prepolymers with at least two recurring flexibilizing structural components. Examples of these are hydroxyl-terminated polyethers based on Polypropylene and polybutylene glycol as well as hydroxyl-terminated polycaprolactones. The Molecular weight (number average) of these prepolymers is generally 150-4000, preferably 500-2500. Prepolymeric structural components can be functional with difunction or higher functionality be, preferably di- or trifunctional. Are low molecular weight components often difunctional. However, the polyesters can also have low molecular weight, contain more highly functional components, preferably in small quantities. At all In these embodiments, the type, functionality, and amount of more functional Components to be chosen so that a polyester with the above specifications arises.

Examples of suitable hydroxyl-terminated prepolymers with at least two recurring flexibilizing structural units are polyethers, polyesters or polythioethers, provided that these compounds are hydroxyl-terminated. Examples of hydroxyl-terminated polyethers are polyalkylene ether polyols which, by ionic polymerization, copolymerization or block copolymerization of alkylene oxides, such as ethylene oxide, propylene oxide or butylene oxide, optionally in the presence of di- or polyfunctional alcohols, such as butane-1,4-diol, 1,1, 1-trimethylolethane, 1,1,1-trimethylolpropane, hexane-1,2,6-triol, glycerol, pentaerythritol or sorbitol, or of amines, such as methylamine, ethylenediamine or hexane-1,6-diamine, or by ionic polymerization or Copolymerization of cyclic ethers, such as tetrahydrofuran, ethylene oxide or propylene oxide, with acidic catalysts, such as BF _3. Etherate, or by polycondensation of water-releasable polyols, such as hexane-1,6-diol, in the presence of acidic etherification catalysts, such as p-toluenesulfonic acid. It is also possible to use oxyalkylation products of phosphoric acid or phosphorous acid with ethylene oxide, propylene oxide or butylene oxide. Examples of hydroxyl-terminated polyester polyols are compounds which are derived from di- and / or polycarboxylic acids and di- and / or polyols, preferably from dicarboxylic acids and diols. Examples of suitable polyols and polycarboxylic acids are those listed here as structural components for the polyesters. Further examples of suitable hydroxyl-terminated prepolymers are polymerization products of lactones, for example of ε-caprolactones; or polyalkylene thioether polyols, for example the polycondensation products of thiodiglycol with and with diols and / or polyols, such as, for example, hexane-1,6-diol, triethylene glycol, 2,2-dimethyl-1,3-propanediol or 1,1,1-trimethylolpropane. These compounds are known per se to the person skilled in the art. They can be linear or branched; the linear types are preferred.

Examples of aliphatic dicarboxylic acids that are used as structural components for Suitable polyesters according to the invention can be saturated aliphatic dicarboxylic acids, such as oxalic acid, malonic acid, succinic acid, α-methyl succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, Sebacic acid or dimerized linoleic acid; or unsaturated aliphatic Polycarboxylic acids, such as maleic acid, fumaric acid, mesaconic acid, citraconic acid, Glutaconic acid or itaconic acid, as well as possible anhydrides of these acids. examples for Cycloaliphatic dicarboxylic acids are hexahydrophthalic, hexahydroisophthalic or Hexahydroterephthalic acid, tetrahydrophthalic, hexahydroisophthalic or Hexahydroterephthalic acid or 4-methyltetrahydrophthalic acid, 4-methylhexahydrophthalic acid or endomethylene tetrahydrophthalic acid. examples for Aromatic dicarboxylic acids are phthalic, isophthalic and terephthalic acid. examples for Highly functional carboxylic acids are aromatic tri- or tetracarboxylic acids, such as Trimellitic acid, trimesic acid, pyromellitic acid or benzophenonetetracarboxylic acid; or trimerized fatty acids or mixtures of dimerized and trimerized fatty acids, such as are commercially available, for example, under the name Pripol®.

Preferred polyol are hexanediol, neopentyl glycol or cyclohexanedimethanol or Combinations of these. Preferred polycarboxylic acids are α, ω-dicarboxylic acids with aliphatic segments such as Adipic or sebacic acid.

The polyester is produced in a manner known per se by reacting the Polyol component (s) with an excess of polycarboxylic acid component (s). Instead of the polycarboxylic acid can also use a polyester-forming derivative, for example an anhydride. Another method of preparation involves condensing polyol and polycarboxylic acid (derivative), the polyol being used in excess. The The resulting prepolymers with hydroxyl groups are then mixed with carboxylic anhydrides capped to carboxyl-terminated polyester. One can continue from the others, too hydroxyl-terminated prepolymers described above, and this with suitable carboxylic acid anhydrides.

The polyester resins can by general procedure used in the production of such Resins find application, are manufactured. So you can expediently Esterification by melt condensation of the carboxylic acid component (s) and the diol carry out. The reactants are stirred, for example Temperatures heated up to 250 ° C. It can offer an inert gas, such as for example nitrogen, to pass through the reaction mixture to the during the Esterification reaction to remove water formed. In the end, too Esterification reaction may be applied a slight vacuum to residual isolate low-molecular cleavage products. The preferred temperature range of the Melt condensation is 160-250 ° C. But you can also use other forms of Apply polycondensation, for example interfacial polycondensation, the Polycondensation in solution, in suspension or in bulk. The condensation of Polycarboxylic acids and / or polyols with functionalities greater than two take place in the Those skilled in the art in a manner known per se under conditions and with stoichiometric Ratios so that gelation is prevented and branching of the polyester is effected.

The compositions according to the invention generally contain 0.2 to 25 % By weight of the compounds which have one or more carboxyl groups. For low molecular weight carboxylic acids such as z. B. were mentioned in the front, 10 are sufficient % By weight in practically all cases. In this case, a content of 0.5 is preferred up to 5% by weight. High molecular weight compounds, such as the described polyesters, As a rule, larger quantities must be used, since these compounds are usually used fewer carboxyl equivalents, based on the amount of the compounds used, contain. In these cases, a content of 10 to 25% by weight is preferred.

The curable compositions can also be other known and customary ones the technology contain radiation and / or heat-curable materials used additives. Examples of such additives are pigments, dyes, flame retardants, Antistatic agents, leveling agents, antioxidants, adhesion promoters, plasticizers, wetting agents, Thixotropic agents, light stabilizers, in some cases also fillers.

Another object of the invention is a method for producing Prepregs using the compositions described above.

In the process, one of the compositions according to the invention is heated Exclusion of UV radiation to a temperature that is between 60 and 140 ° C and is at least so high that the composition has a viscosity of at most about 3500 mPa · s, preferably at most 1200 mPa · s, brings the composition with further UV exclusion in this state with a fibrous material in intimate contact, cools the treated fiber material with exclusion of UV radiation at least to a temperature at which the hardenable mixture solidifies and activates the material obtained thereafter either after intermediate storage UV exclusion or immediately by exposure to UV radiation.

In principle, all fibers suitable with the Epoxy matrix can form a composite and a reinforcement of the matrix material cause. Examples of fiber materials are natural polymers such as cellulose; Metal fibers, e.g. B. made of steel, Ti, W, Ta or Mo; Glass and ceramic fibers; organic fiber-forming polymers, especially aromatic polyamides, such as Nomex or Kevlar; but also carbon fibers, e.g. by carbonizing cellulose, polyacrylonitrile or Pitch made materials.

The fiber materials can be used in various forms as supports. They can be used, for example, as continuous threads (individual threads or spun threads), Continuous yarns, parallel rovings, as woven continuous yarns, spinning rovings, roving fabrics, Use short fibers, continuous mats, cut mats, nonwovens or felts (papers).

Contacting the fibrous material with the curable resin composition will vary depending on the fiber type and shape. For example Prepregs containing short fibers by applying the flowable, hardenable ones Composition together with cut fibers on a fabric or Metal foil can be produced. A preferably flexible carrier can also be used first with the hot, flowable mixture can be coated and the fiber material can on one later point where the coating is still flowable enough, e.g. B. with a press roller are incorporated into the coating, after which the carrier may be removed again becomes. Squeegee application is also possible. For this and for similar order types the viscosity of the hot compositions according to the invention is preferably 3500 up to 1200 mPas. Contacting the fibrous material with the curable Mixture can also be impregnated with fabrics, nonwovens or continuous fibers a curable composition heated to flowability, such as to be used according to the invention, take place, the fabric sheets from the Fiber material, for example, go through a bath with the hot composition. At The impregnation should preferably have the compositions according to the invention Viscosity from 1200 to 200 mPa · s and for example temperatures between 100 and Have 120 ° C. A preferred method of this type is the fiber winding method, such as it is explained in more detail below in Example 5.

During processing, the temperature of the compositions according to the invention can can easily be increased to well over 100 ° C to achieve the required viscosity of at most 3500 mPa · s or a viscosity of preferably at most 1200 mPa · s adjust. As long as the temperature is kept below approx. 140 ° C, there is generally no risk of (partial) premature hardening of the Resin composition, and after the following cooling a chemically im essentially unchanged, dry at room temperature, hardly any sticky and solid mass. The cooling mentioned takes place preferably Room temperature, ie. to approx. 10 to 25 ° C.

Since the curable used according to the invention for the production of prepregs Compositions that are sensitive to UV radiation must do both Contact as well as cooling down with the exclusion of UV radiation respectively. Light of longer wavelengths, e.g. B. yellow light, however, may be present.

The prepreg material obtained on cooling can be rolled up into rolls, for example will be or be assembled in any other way. It can be in this Form under UV exclusion at room temperature if desired for months, e.g. B. 5 to Can be stored for 15 months or longer without sacrificing quality. A Storage in the refrigerator is, of course, for an even longer period than with Room temperature possible. The material can also be processed immediately.

For this purpose, the prepreg material obtained is subjected to the action of UV radiation, preferably one Wavelength of 200 to 450 nm, exposed, which makes it suitable for curing low temperature activated form is transferred. Are suitable as light sources for example xenon lamps, argon lamps, tungsten lamps, carbon arcs, Metal halide and metal arc lamps, such as low pressure, medium pressure and High-pressure mercury lamps or lasers, such as argon or krypton ion lasers. The irradiation with metal halide or High pressure mercury lamps carried out. The irradiation time depends on various factors, including e.g. the polymerizable organic Material, the type of light source and its distance from the irradiated material. The Irradiation time is preferably 1 to 120 seconds.

In the activated form mentioned above, the material is still some time storable, generally 2 to 7 days at room temperature and 3 to 5 weeks in the refrigerator.

From the activated prepregs z. B. composite or laminates or Laminates are made. Such composite bodies can, for. B. but also flat plates parts of any shape, such as boats or boat parts, masts for surfboards, skis, Tennis racket or bicycle frame.

To produce the composite body, a layer of the prepreg material is either on another or placed on a layer of another suitable material, any Can have shape, and this process repeated as often as desired so that a layer sequence is created from the materials used. Common examples of other materials are plastic or metal foils, such as copper and aluminum foils, or other reinforcing agents, such as mats or nonwovens made of fibrous Reinforcement material.

The layer sequence is then between 1 and 60 minutes at a temperature between 50 and 140 ° C pressed, after which the finished composite body is obtained. The pressure is generally between 0.3 and 60 bar. The exact coordination of the As the expert knows, press parameters also depend on the material and must if necessary be optimized.

The prepregs are also particularly suitable for use lower and very low pressures, e.g. B. 0.5 to 20 bar, in particular 0.5 to 10 bar. Pressing pressures below 1 bar can also be easily applied to the entire surface irregularly shaped workpieces are created, for example by a suitable pressing tool, such as a flexible hollow body, inside which you can The workpiece to be pressed is partially or completely evacuated from the inside, so that the Hollow body hugs the surface of the workpiece and the external air pressure as Press pressure acts on the workpiece. Furthermore, e.g. B. continuously in Belt presses or also in floor presses (discontinuously) are pressed. Composite bodies are preferably produced during 10 to 60, in particular 10 to 20 minutes at a temperature of 80 to 120 ° C, especially 80 to 100 ° C.

The compounds with one or more carboxyl groups are according to the present invention therefore the compositions based on epoxy resins and compounds of formula I added because it has been shown that such Although compositions often without the presence of these compounds Temperatures between 60 and 140 ° C are thermally hardened to a certain degree in the presence of compounds containing carboxyl groups this hardening with the same amount of time, but to a networking of unexpectedly higher dimensions leads to that which is achieved during the same time when the carboxyl compounds are not present. This is especially true with compositions that are very have a high proportion of solid epoxy resins. The use of compounds that have one or more carboxyl groups for the purpose described above, i. H. as an additive to compositions made from epoxy resins, in particular from a Mixture of liquid and solid epoxy resins with a proportion of solid epoxy resins of over 50% by weight, based on the total weight of the epoxy resins, of compounds of the formula I. in the meaning described above and, if appropriate, customary additives exist, and as an additive, the thermal cross-linking with UV radiation exposed compositions in the temperature range of 60 to 140 ° C, in particular from 80 to 100 ° C, is therefore also an essential part of the present Invention. So show prepregs that according to the invention with the help of curable Compositions are obtained and contain carboxyl-containing polyesters, after fifteen minutes of heating to 100 ° C in general already a degree of hardening of 90% and more, while prepregs based on appropriate mixtures without the Polyester or another carboxyl compound only after 60 minutes at 100 ° C Show degrees of hardening in the range of 70 to 80%. This applies to the degree of hardening Hundred times the difference of using differential scanning calorimetry (DSC) certain enthalpy of reaction when heating a completely fresh Resin composition or a completely fresh prepreg is measured, and the Enthalpy of reaction, which is to be measured in a similar sample, is already Undergoes curing under the conditions under consideration, based on the first called reaction enthalpy.

The use of low molecular weight carboxyl compounds, e.g. B. of connections with an equivalent weight of 45 to 250 g per carboxyl equivalent, in particular 45 up to 100 g, has the advantage that promotion of sales already in the hardening with a small addition of the carboxyl compounds, e.g. B. with 0.2 to 10 wt .-% can be reached. Here is the use of lactic acid, adipic acid and fumaric acid is particularly preferred.

The prepregs according to the invention both have excellent adhesive properties among themselves as well as on other materials, especially on metals such as copper, Aluminum and aluminum alloys, or on plastics, especially on ABS, Phenol-formaldehyde and melamine-formaldehyde condensation products, hardened Epoxy resins and rubber.

The glass transition temperature (T _G ), which show hardened prepregs, can be controlled by the person skilled in the art, e.g. B. by the selection of suitable epoxy resins. In order to keep thermal stresses in a composite body low, it is in many cases advantageous to aim for a glass transition temperature that is as low as possible, but still sufficient in view of the thermal load to be expected of the composite body. For skis, boots and bicycle construction z. B. prepreg material that provides T _G values down to 75 to 80 ° C, are used well, while for the production of tennis rackets prepreg material for higher T _G values, e.g. B. 120 to 140 ° C, may be cheaper.

Unexpectedly, it has also been shown that even prepreg material based on Sufficient amounts of carbon fibers can be activated with the help of UV radiation can harden at the above temperatures. This is surprising because coal practically completely absorbs UV radiation, i.e. one activation much less complete than when using UV-permeable fiber material was to be expected. In a special embodiment of the inventive The process therefore uses a fibrous material based on carbon fibers, and prepregs are obtained which are preferred at a temperature of 60 to 140 ° C from 80 to 120 ° C, essentially completely can be cured.

example 1

53.9 parts by weight (one part by weight corresponds to 1 g below) of Araldit® GT 7071 (solid epoxy resin based on bisphenol A with a softening point of 77 - 82 ° C and an epoxy content of 1.9 - 2.0 equivalents per kilogram) at a temperature of 120 - 130 ° C in 34.3 parts by weight Araldit® LY 556 (liquid epoxy resin based on bisphenol A with an epoxy content of 5.25 - 5.40 equivalents per kilogram) and the mixture homogenized well. When everything is well homogenized, the mixture is cooled to a temperature of 90 ° C. with stirring, and 9.8 parts by weight of a carboxyl-terminated polyester made of polytetrahydrofuran (number average molecular weight 1000), neopentyl glycol and fumaric acid, which has a viscosity of 26880 mPa · s ( 25 ° C), has an acid number of 63.3 mg KOH / g and a number average molecular weight of 4300. Subsequently, 2 parts by weight of (η ^6- cumol) (η ⁵ -cyclopentadienyl) Fe-II-hexafluoroantimonate are dispersed in the mixture at a temperature of 75 ° C. using a dispermate under yellow light.

The following values were measured for the viscosity of this mixture: Temperature [° C] Viscosity [mPa · s] 80 3360 100 1120 120 360 Its softening point is 5.9 ° C.

The same results are obtained when you look at the temperature of the mixture during the whole manufacturing process described above not below 120 ° C can sink.

A glass fabric mat (Interglas IG 92146) is with yellow light with the on a Temperature impregnated from 100 to 120 ° C heated mixture. You get after Cool down a slightly sticky, flexible prepreg with a resin content of approx. 30 to 40 % By weight at z. B. can be stored for 15 months without loss of quality.

The prepreg is removed with a UV lamp ("dust") Metal halide copying lamp ULTRALUX® 500 K) of 2000 watts of power twice exposed for 1 minute. The activated prepreg obtained is at least 2 days at 23 ° C. Can be stored at 8 ° C for approx. 3 weeks without loss of quality.

The same results are obtained when the exposure with an appropriate Lamp of 200 watt power at a distance of 0.10 meters for two 10 minutes or in daylight behind window glass for 2 hours for two hours.

With the help of a differential scanning calorimeter measurement (DSC), the course of the thermal curing reaction of an activated prepreg of the above composition is followed. A Mettler thermal analyzer TA 4000-TC 11 with a DSC measuring cell DSC 25 is used for the measurement. Under yellow light, 10 to 20 milligrams of a freshly activated prepreg sample or of activated prepreg samples that have been subjected to thermal curing under the specified conditions are filled into a DSC measuring bowl, the bowls are closed and heated at a rate of 10 ° C per minute heated up. Each time, the device automatically delivers the temperature at the reaction maximum and, after integration of the DSC peak, the reaction enthalpy and, if necessary, the glass transition temperatures T _Go (at the start of softening) and T _G (temperature at the turning point of the stage). From the difference of the reaction enthalpy, which is measured in a fresh prepreg sample, and the reaction enthalpy, which is measured in a prepreg sample, which has already been subjected to a specific hardening, the degree of hardening which can be achieved when hardening under these conditions can then be determined.

Temperatur beim Reaktionsmaximum der frischen Prepregprobe

101°C

Härtungsbedingungen T_Go/ T_G [°C] Härtungsgrad [%] 15 min 100 °C 73 80 95 60 min 100 °C 86 95 96 Man erkennt, dass bereits eine 15-minütige Härtung bei 100 °C praktisch vollständig ist.The following values are obtained:

Temperature at the reaction maximum of the fresh prepreg sample

101 ° C

Curing conditions T _Go / T _G [° C] Degree of hardening [%] 15 minutes 100 ° C 73 80 95 60 min 100 ° C 86 95 96 It can be seen that curing for 15 minutes at 100 ° C is practically complete.

After curing for 15 minutes at 100 ° C., the prepregs obtained according to this example show a tensile shear strength on ground aluminum of 11.4 N / mm ² (determined in accordance with ISO 4587/79 with a 12.5 mm overlap).

The roll peel strength after curing for 20 minutes (incl. Heating time) at a temperature of 100 ° C, determined according to ISO 4578/79, is: aluminum 1.5 N / mm ² , rubber 4.3 N / mm ² , SECTION 0.7 N / mm ² , PURE 0.6 N / mm ² , PE, painted 3.8 N / mm ² . 12 layers of the prepregs described are placed on top of one another and pressed between separating foils in a press heated to 100 ° C. for 60 minutes up to the stop on a 3.2 mm spacer frame to form a laminate plate of appropriate thickness. The interlaminar shear strength according to ASTM D 2344/84 is 51.1 ± 0.5 MPa for this plate.

Comparable results can also be obtained with a composition of 59.5 parts by weight of Araldit® GT 7071; 30 parts by weight of Araldit® LY 556, 10 parts by weight of the polyester from Example 1 and 0.5 part by weight of (η ⁶ -cumene) (η ⁵ -cyclopentadienyl) Fe-II-hexafluoroantimonate can be obtained.

Examples 2 to 4

As described in Example 1 and using the same solid and liquid epoxy resin component and the same UV activator (η ^6- cumol) (η ⁵ -cyclopentadienyl) Fe-II-hexafluoroantimonate, the mixtures given in the table below were prepared. example 2nd 3rd 4th Parts by weight of liquid epoxy resin 50 25th 25th Parts by weight of solid epoxy resin 50 60 60 Parts by weight of UV activator 2nd 2nd 2nd Parts by weight / type of carboxyl compound 1 / fumaric acid 15 / polyester A 15 / polyester B Polyester A = polyester from neopentyl glycol and adipic acid in approximate Molar ratio 7 to 8; Viscosity at 25 ° C: 18000-25000 mPa · s; 1.25 - 1.43 acid equivalents per kilogram.

Polyester B = polyester made of polytetrahydrofuran (number average molecular weight 1000), neopentyl glycol and sebacic acid; Viscosity at 25 ° C: 26880; Number average of the Molecular weight: 4300; Acid number 6.2 milligrams of KOH per gram of polyester.

The following measured values for the temperature at the reaction maximum, the degree of hardening, T _Go and T _G , the interlaminar shear strength, the tensile shear strength on aluminum and the roll peel strength are obtained in accordance with the regulations used in Example 1: example 2nd 3rd 4th Softening point [° C] 2.3 4.1 - Temperature at the maximum reaction 109 106 110 Degree of hardening [%] 15 min / 100 ° C - 90 91 60 min / 100 ° C 81 93 97 T _Go / T _G after curing at 60 min / 100 ° C [° C] 83/91 70/75 66/74 Interlaminar shear strength [N / mm ² ] 51.1 ± 0.5 32.9 ± 2.4 23.5 Tensile shear strength on aluminum [N / mm ² ] - 11.2 9.1 Roll peel strength [N / mm ² ] 1.3 ± 0.1 - -

a) 75 Gewichtsteile Araldit® GT 7071 (festes Epoxidharz auf Basis von Bisphenol A mit einem Erweichungspunkt von 77 - 82 °C und einem Epoxidgehalt von 1,9 - 2,0 Äquivalenten pro Kilogramm) wird bei einer Temperatur von etwa 120 °C in 15 Gewichtsteilen Araldit® LY 556 (flüssiges Epoxidharz auf Basis von Bisphenol A mit einem Epoxidgehalt von 5,25 - 5,40 Äquivalenten pro Kilogramm) gelöst und das Gemisch gut homogenisiert. Wenn alles gut homogenisiert ist, werden 10 Gewichtsteile eines carboxylterminierten Polyesters aus Polytetrahydrofuran (Zahlenmittel des Molekulargewichtes 1000), Neopentylglycol und Fumarsäure, der eine Viskosität von 26880 mPa·s (25 °C), eine Säurezahl von 63,3 mg KOH/g und ein Zahlenmittel des Molekulargewichtes von 4300 aufweist, zugegeben. Anschliessend werden in dem Gemisch unter Gelblicht 2 Gewichtsteile (η⁶-Cumol)(η⁵-cyclopentadienyl) Fe-II-hexafluoroantimonat dispergiert.
Für die Viskosität dieser Mischung wurden folgende Werte gemessen: Temperatur [°C] Viskosität [mPa·s] 100 5120 120 1480 130 860 140 520

b) Die gesamte Imprägnierung des Glasfaserstranges erfolgt in einem Raum mit Gelblicht. Hierbei wird ein metallener doppelwandiger Trichter mit zirkulierendem heissen Öl auf ca. 140 °C beheizt. Der Trichter hat unten eine Austrittedüse von ca. 1 Millimeter Durchmesser, durch die der Glasfaserstrang hindurchgeführt wird. Etwa einen Meter unterhalb der Düse befindet sich eine Vorrichtung zum Aufwickeln des imprägnierten Stranges auf eine Kartonhülse. Die oben beschriebene Zusammensetzung wird abgekühlt, in Brocken zerschlagen und in dieser Form in den Trichter eingebracht. An den heissen Wänden des Trichters beginnt sie sofort zu schmelzen. Wenn sich über der Düse genügend Schmelze angesammelt hat, wird der Glasfaserstrang durch die Düse gezogen und auf die Kartonhülse aufgewickelt. Hierbei durchdringt das Harz den Faserstrang vollständig. Zwischen der Düse und der Aufwickelvorrichtung wird der Strang mit Hilfe zweier Kaltluftgebläse abgekühlt, so dass er trocken und klebfrei ist und einen Harzgehalt von 22,7 Gewichtsprozent aufweist. Man kann den imprägnierten Strang auch nach mehrwöchiger Lagerung bei Raumtemperatur problemlos wieder von der Kartonhülse abwickeln, ohne dass er dabei zerstört würde.

c) Herstellung eines Rohres nach dem Faserwickelverfahren mit Hilfe des oben beschriebenen imprägnierten Glasfaserstranges.

Example 5: Production of dry prepreg rovings (glass fiber strands impregnated with the "prepreg resin").

a) 75 parts by weight of Araldit® GT 7071 (solid epoxy resin based on bisphenol A with a softening point of 77 - 82 ° C and an epoxy content of 1.9 - 2.0 equivalents per kilogram) is in at a temperature of about 120 ° C 15 parts by weight of Araldit® LY 556 (liquid epoxy resin based on bisphenol A with an epoxy content of 5.25 - 5.40 equivalents per kilogram) were dissolved and the mixture was homogenized well. When everything is well homogenized, 10 parts by weight of a carboxyl-terminated polyester made of polytetrahydrofuran (number average molecular weight 1000), neopentyl glycol and fumaric acid, which has a viscosity of 26880 mPa · s (25 ° C), an acid number of 63.3 mg KOH / g and has a number average molecular weight of 4300 added. Subsequently, 2 parts by weight (η ^6- cumol) (η ⁵ -cyclopentadienyl) Fe-II-hexafluoroantimonate are dispersed in the mixture under yellow light.
The following values were measured for the viscosity of this mixture: Temperature [° C] Viscosity [mPa · s] 100 5120 120 1480 130 860 140 520

b) The entire impregnation of the glass fiber strand takes place in a room with yellow light. A metal double-walled funnel is heated to approx. 140 ° C with circulating hot oil. The funnel has an outlet nozzle of approx. 1 millimeter in diameter through which the glass fiber strand is passed. About one meter below the nozzle is a device for winding the impregnated strand onto a cardboard tube. The composition described above is cooled, broken into chunks and introduced into the funnel in this form. It immediately begins to melt on the hot walls of the funnel. When enough melt has accumulated above the nozzle, the glass fiber strand is pulled through the nozzle and wound onto the cardboard tube. The resin completely penetrates the fiber strand. Between the nozzle and the winding device, the strand is cooled with the aid of two cold air blowers, so that it is dry and tack-free and has a resin content of 22.7 percent by weight. Even after several weeks of storage at room temperature, the impregnated strand can easily be unwound from the cardboard tube without being destroyed.

c) Production of a tube by the fiber winding process with the aid of the impregnated glass fiber strand described above.

The winding mandrel (40 millimeters in diameter) of a conventional fiber winding system is opened 100 ° C preheated. Instead of the usual impregnation bath, the fiber winding system a device with which the impregnated glass fiber strand from the cardboard tube can be handled. Between this unwinding device and the hot mandrel there is a housing with a feedthrough for the fiber strand, inside it a medium pressure mercury UV lamp and various reflectors so arranged are that the fiber strand is irradiated evenly from all sides. Now be on a length of 30 centimeters, four layers of the fiber strand wound up one above the other. Here, the impregnating compound becomes liquid again, so that it lies side by side Merge fiber strands. The wrapping process is finished after about two minutes and after a short time the resin on the hot mandrel begins to gel. After 30 Minutes the thorn is removed. You get a transparent tube, the Glass transition temperature is 89 ° C. The reaction conversion is 93%.

This method has some special advantages for the user. So he has to Users no longer necessarily impregnate the fiber strands themselves, as was previously the case , but he simply gets the impregnated, storable fiber material from one Manufacturer. There are no resin losses due to being too short or incorrect estimated pot times and unused resin residues and they are only very short Curing times at relatively low curing temperatures required. But even those who have impregnated fiber material for themselves or for resale Advantages when using the compositions according to the invention, since these in general one-component mixtures and are therefore no mixing errors of resin and Harder conditions can occur, leading to fluctuations in the properties of the prepreg material being able to lead.

Claims (9)

1. A curable resin composition containing less than 2 per cent by weight of solvent for the fabrication of prepregs, which contains more than 45 per cent by weight of substances which are solid at ambient temperature at least, and which consists, in addition to customary additives, of solid epoxy resins or a mixture of liquid and solid epoxy resins, at least one initiator which is sensitive to UV radiation for the polymerisation of the epoxy resins and has the formula I [R1(FeIIR2)a]ab+ ab[X]- in which a and b are each independently of the other 1 or 2, R¹ is a π-arene, R² is a π-arene, an indenyl anion or a cyclopentadienyl anion, [X]^- is an anion [LQ_m]^- or the anion of a partially fluorinated or perfluorinated aliphatic or aromatic sulfonic acid, L is B, P, As or Sb, Q is F, with the proviso that some of the radicals Q may also be hydroxyl groups, and m is the valency of L increased by one, and at least one further compound which contains one or more carboxyl groups, and the content of solid epoxy compounds is 50 per cent by weight or more than 50 per cent by weight, based on the total weight of the epoxy resins in the composition, which composition, by heating to a temperature in the range from 60 to 140°C, excluding UV light and without the addition of a solvent, is convertible into a state in which it has a viscosity not higher than 3500 mPa·s, and, by cooling to a temperature not exceeding ambient temperature and excluding UV light, can be converted from this state into a solid mass which is still uncured which is tack-free or substantially tack-free at ambient temperature and which has a softening point of minus 3°C or more.
2. A composition according to claim 1, which is convertible by said heating to a temperature in the range from 60 to 140°C into a state in which it has a viscosity of from 200 to 3500 mPa·s.
3. A composition according to claim 1 or 2, which contains altogether from 60 to 98 % by weight of epoxy resins.
4. A composition according to at least one of claims 1 to 3, which contains as liquid epoxy resins either glycidyl esters or diglycidyl ethers which are derived from 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) or from bis(4-hydroxyphenyl)methane (bisphenol F).
5. A composition according to at least one of claims 1 to 4, which contains as solid epoxy resins polyglycidyl ethers which are derived from 2,2-bis(4-hydroxyphenyl)propane (bisphenol A), bis(4-hydroxyphenyl)methane (bisphenol F) or from epoxy novolaks, especially from epoxy phenol and epoxy cresol novolaks.
6. A composition according to at least one of claims 1 to 5, which as the compound containing one or more carboxyl groups contains fumaric acid, lactic acid and/or adipic acid.
7. A composition according to at least one of claims 1 to 4, which as the compound containing one or more carboxyl groups contains polyesters terminated with on average at least two carboxyl groups per molecule.
8. A process for the fabrication of prepregs, in which a composition according to claim 1 is heated, excluding UV light, to a temperature which is between 60 and 140°C and is at least sufficiently high that the composition has a viscosity not higher than 3500 mPa·s, preferably 1200 mPa·s, the composition is brought into intimate contact in this state with a fibrous material, still excluding UV light, the fibre material thus treated is cooled, excluding UV light, at least to a temperature at which the curable mixture solidifies, and the material obtained is activated for a thermal cure either after initial storage, excluding UV light, or immediately by exposure to UV radiation.
9. A process according to claim 8, in which the fibrous material employed comprises carbon fibres.